Error message: .mov clip not compatible with QuickTime...

I downloaded a few .mov clips and got the error message that the file wasn’t compatible with QuickTime. Been subscribing to Envato for years and never got this message. Weird, especially because it wasn’t just the one clip but about four that generated the same error message. Tried to re-download the clips, but the same message popped up.
I need the alpha to stack clips and I know there are workarounds, but having a ready to go clip is much more convenient.
Is this a temporary glitch?